Would it be better to modify the factory box and put on a Cone K&N or buy one like ZZP?

 

K&N intake, hands down best intake for the car.

 

K&N. i had one on my car for the longest time and loved that thing. they say the sri get all the heat from the motor but you couldnt tell me that because i still made 357whp 375wtq on the sri lol

 

Awesome!

 

I have run the K&N for a long time too.

It runs fine. But I can tell you from my recent logging, that the car is running 10-15% too lean in the upper RPMs on GM Stage 1. So you really should get a tune to be safe with all intakes.